Investigation of Fracture Behavior in Mode I and II for Repaired Edge-Inclined Cracks with Trapezoidal Composite Patches

Abstract

Numerous studies have shown the effectiveness of composite patch repairs. However, many of these investigations primarily address the enhancement of repaired components' lifespans, focusing mainly on opening mode (Mode I). In real-world applications, cracked components often undergo mixed mode loading that includes both Modes I and II. This article examines the stress intensity factors for Modes I and II in relation to the fracture behavior of a tensile-loaded aluminum plate (Al 7075) featuring a 45° inclined lateral crack repaired on both sides with a unidirectional graphite/epoxy composite trapezoidal patch. A three-dimensional finite element model of the repaired specimen is employed to explore how composite patching affects critical crack tip parameters (KI, KII, and stresses). This approach demonstrates how the properties of the composite and adhesive impact the repaired structure's behavior and the effectiveness of the bonded composite patch. The findings reveal that trapezoidal composite patch can significantly reduce the stress intensity factors KI and KII, thereby extending the service life of cracked structures.